Instructor Selection: event signups listing

[pbanaszkiewicz]

As an admin user, I want to see listing of all signups for the event. I also want to see a global page with signups from all events grouped by event.

Acceptance criteria:

1. On single event listing: display list of signups (name, taught statistics, country, notes from instructor, notes from admin, potential date conflicts, interest [whole session, part session, supporting instructor], "actions" column)
2. On all events listing, additionally include notes from event recruitment.
3. Note whether workshop is online or in-person and include workshop dates
4. On all events listing, events should appear in ascending chronological order (most recent first)
5. On all events listing, the view should allow for filtering based on admin assignment (default assigned to self)